1. Field of the Invention
This invention relates to a method for the enhancement of a polymeric biguanide based water sanitizing system and to the conversion of such a system to a halogen based or alternative based water sanitizing system.
2. Background of the Invention
There are many methods available for the control of the growth of bacteria and algae in aqueous systems such as pools and spas. Traditionally, halogen based systems have been used as sanitizers that have included the use of chlorine in doses of 1 to 10 parts per million. But another popular sanitizing system that has been widely adopted is based upon the use of polymeric biguanide as described in U.S. Pat. No. 4,014,676. Such polymeric guanide-type systems have been popular because they do not cause eye irritation that is common with chlorine based systems and because polymeric guanide-based systems have been thought to be less expensive because it has been believed that smaller quantities of chemicals are required when compared with chlorine based systems. Baquacil.RTM. sold by ICI Americas, Inc. is the primary polymeric biguanide-based product in the market today. A similar polymeric product is Softswim.RTM. manufactured by Biolab, Inc. and another polymeric sanitizer is sold under the tradename Sustain.RTM. by PPG, Inc. located at 1 PPG Place, Pittsburgh, Pa. 15272.
Unfortunately, it has been observed that algae are able to become resistant to the sanitizing effects of polymeric guanide-based systems. When this occurs, polymeric biguanide based pools are typically treated with products that contain hydrogen peroxide as their active ingredient. For example, Baquashock.TM. is one such product containing a solution of 28% hydrogen peroxide, which has a very short activity in a swimming pool. These products are not always effective, and the unsightly algae continues to grow unchecked. In addition to various algae, it has been reported that persistent blooms of bacteria having a reddish-pink appearance and water molds have developed in polymeric biguanide based pools. In many cases, treatment with products such as Baquashock.TM. have no effect on these problems as well.
In addition, linear quaternary algicides have been employed in attempts to bring algae containing Baquacil pools under control, but such algicide have only experienced limited success. Other approaches have included shock treatment with chlorine or potassium monopersulfate, but such shock treatments have resulted in plugged filters, stained pool walls, and pool water having a muddy appearance.
The same problems have been observed with respect to other polymeric systems such as polymeric quaternary ammonium based sanitizing systems. Because of these problems associated with polymeric biguanide and polymeric quaternary pools, it is frequently desired to return the pool to a chlorine based sanitizing system to eliminate the microbial life forms that have taken over the pool. Unfortunately, the prior art teaches that polymeric guanide-based systems are incompatible with halogen systems. When bromine or chlorine is added directly to a body of water using a polymeric biguanide-based system, the halogen reacts rapidly with the biguanides to produce organic precipitates that give the pool an aesthetically unpleasant appearance. For this reason, the prior art teaches that the pool must be drained and refiled with fresh water if one desires to convert to a halogen based system from a polymeric biguanide-based system. Obviously, the prior art approach is time consuming, costly, and environmentally undesirable.